As if that’s not enough, they will take another dive early Monday, this time to minus 28.

The National Weather Service warned that strong winds would dunk the mercury in the upper plains states and plunge wind chill factors to as low as minus 50 degrees Fahrenheit.

High temperatures Monday are predicted to stay below zero.

The Centers for Disease Control warns people in extremely cold areas to stay in heated rooms and keep outdoor trips brief.

At 30 below zero, frostbite can occur in as little as 10 minutes with the slightest winds, and in five minutes in a brisk breeze, the CDC warns. Newborns, the elderly and the homeless can quickly fall victim to hypothermia.

“Cold weather puts an extra strain on the heart,” the CDC said, and overexertion can become even more dangerous to those with heart conditions in the Arctic cold.

Although such deep freezes are potentially deadly, they are not uncommon in the upper midsection of the United States. The North Dakota Department of Emergency Services said it did not deploy additional staffing because of the weather.